SELECT 
  cscart_products.* 
FROM 
  cscart_products 
WHERE 
  cscart_products.product_id IN (
    9821, 9822, 9823, 9824, 9825, 9826, 9827, 
    9828, 9829, 9830, 15732, 9797, 9798, 
    9799, 9800, 9801, 9802, 9803, 9804, 
    9805
  )

Query time 0.00103

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_products",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 20,
      "filtered": 100,
      "index_condition": "cscart_products.product_id in (9821,9822,9823,9824,9825,9826,9827,9828,9829,9830,15732,9797,9798,9799,9800,9801,9802,9803,9804,9805)"
    }
  }
}